Ultrashort and short-pulse laser ablation for chemical element analysis and thin film deposition of complex materials

Abstract

Ultrashort and short high-power laser pulses are employed to ablate metallic and oxide materials, to analyze their element composition by laser-induced breakdown spectroscopy (LIBS), and to grow complex oxide thin films by pulsedlaser deposition (PLD). With ultrashort femtosecond (fs) lasers the ablated mass per laser pulse can be reduced compared to short nanosecond lasers. This enables chemical imaging with high spatial resolution. The intensity of atomic emission lines in fs-LIBS spectra is correlated to the ablated mass for metal thin films on glass. The obtained limits of detection are 370 fg for Ag, 100 fg for Cu, and 14 fg for Na. LIBS measurements of industrial steel samples using nanosecond lasers reveal a surprisingly strong matrix effect. The line intensities of analyte elements like Mn are cross-sensitive to other elements like Si. This detrimental matrix effect is overcome when the laser-ablated sample is re-excited by an electric spark discharge (laser ablation-spark discharge-optical emission spectroscopy, LA-SD-OES). Thin films of quasi-2D high-temperature superconducting Bi 2 Sr 2 CaCu 2 O 8+d are grown on LaAlO 3 substrates. The PLD films are epitaxial, stoichiometric, and single-phase and have high critical temperature and critical current densities.